Hi Bill
I mean to pick this up earlier in the week but somehow it slipped
through my net. Sorry.
Anyhows: pack_c.c and pack_f.f are not programs but essentially
subroutine libraries. You would need to write your own program to
actually use them (I'm not sure that there's any documentation
Hi James,
On the gathering of the data from all possible beamline / source /
detector combinations below, I am also keen to get hold of these. To
assist with this I have written a couple of bash shell scripts which
will tar, gzip and split into 128MB chunks data, then reverse this
process to
Hi James,
The old mar345 images were compressed with the pack which Bill is
referring to. This is suppoprted in CBFlib.
PNG and jpeg2000 may well do better at compression (would like to see
the numbers with this) but are likely to be much slower than something
customised for use with diffraction
Hi
Lossy compression should be okay, provided that the errors introduced are
smaller than those expected for counting statistics (assuming that the
pixels are more-or-less independent) - i.e. less than the square-root of
the individual pixel intensities (though I don't see why this can't be
Dear all,
I think we need to stop and think right here. The errors in pixel
values of images are neither Poisson (i.e. forget about taking square roots)
nor independent. Our ideas about image statistics are already disastrously
poor enough: the last thing we need is to make matters even
oopss...Not science:
Proteins: Structure, Function, and Genetics
Volume 16, Issue 3 , Pages 301 - 305 (1993)
-Original Message-
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of
Soisson, Stephen Michael
Sent: Friday, August 24, 2007 10:59 AM
To: CCP4BB@JISCMAIL.AC.UK
Wow.
I don't know about the rest of you, but I got told three times.
Gerard is, of course, right about pixel non-independence (think point
spread function, among other things), and I wouldn't care to argue
statistics with him, but as far as I know (and I could well be wrong) most
of the
Jeremy Berg, Rubredoxin. In Science around 1995.
Steve
-Original Message-
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of
Bernhard Rupp
Sent: Friday, August 24, 2007 10:57 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] centrosymm structure
Dear All,
there was a paper
Hi folks
If you've recently downloaded a pre-built copy of Mosflm version 7.0.1 for
Intel Mac (including the universal binary) and been surprised by the need
for libgfortran.1.dylib, read on. Otherwise, feel free to ignore this!
It seems my attempts to produce a statically linked OS X
My group has several vacancies to fill immediately: a Team Leader for
Infrastructure and Methods Development; two postdoc positions; and a
technician. This is the Protein Crystallography group of the
Structural Genomics Consortium, Oxford.
For details, please see respectively:
Team
On Friday 24 August 2007 12:22, Michel Fodje wrote:
1. In every description of Braggs' law I've seen, the in-coming waves
have to be in phase. Why is that? Given that the sources used for
diffraction studies are mostly non-coherent.
Think of Bragg's Law as explaining what happens to a single
Michel Fodje wrote:
Dear Crystallographers,
Here are a few paradoxes about diffraction I would like to get some
answers about:
...
3. What happens to the photon energy when waves destructively interfere
as mentioned in the text books. Doesn't 'destructive interference'
appear to violate the
1. In every description of Braggs' law I've seen, the in-coming waves
have to be in phase. Why is that? Given that the sources used for
diffraction studies are mostly non-coherent.
Think of Bragg's Law as explaining what happens to a single photon
that is probabilistically scattered by
For every direction where there is destructive interference and a
loss of energy there is a direction where there is constructive
interference that piles up energy. If you integrate over all
directions
energy is conserved.
For the total integrated energy to be conserved, energy will have to
You are just using the coherent fraction of the beam.
My point is that Braggs' law as currently understood does not preclude
the diffraction from waves which were non-coherent before hitting the
sample
It is not clear at all how you arrive to that condition. By definition, if
two waves are non
For the total integrated energy to be conserved, energy will have to be
created in certain directions to compensate for the loss in other
directions. So in a direction in which the condition is met, the total
will have to be more than the sum of the waves in that direction.
How about considering
On Fri, 24 Aug 2007 14:40:13 -0600
Michel Fodje [EMAIL PROTECTED] wrote:
The mathematics works but doesn't necessarily mean the current
interpretation of the mathematics has any resemblance to what actually
happens in reality.
Sure, it does. Crystallography is traditionally
Michel Fodje wrote:
For every direction where there is destructive interference and a
loss of energy there is a direction where there is constructive
interference that piles up energy. If you integrate over all directions
energy is conserved.
For the total integrated energy to be conserved,
Here's a fun way to think of it:
A photon hits a crystal and will diffract off in a certain direction
with the same energy as the original photon. The direction is subject to
a probability distribution based on the lattice, with angles at the
diffraction conditions being most likely and the
Without resorting to a circular argument? You are asking too much.
However, this probability distribution is perfectly described by
considering a component wave model wherein coherence of the component
waves correlates with peaks in the probability distribution--i.e.
Bragg's Law.
IANAM (I
Would it be taking it too far to suggest that one could go all the way
and consider that each electron diffracts not as groups in a plane but
as individual electrons and a photon impinging on an electron with with
a specific phase will be diffracted in a specific direction. However the
lattice
Dear All,
I am working with a protein that requires 10% glycerol throughout the
purification to keep it soluble. I have been very worried that having
glycerol in my protein solution when I am trying to crystallize it will
prevent me from obtaining crystals. I am curious to see if others have
We have crystallised many things with 10% Glycerol. If % is high enough, there
is also often the added bonus in that the crystals are naturally cryoprotected!
J
Edward Berry [EMAIL PROTECTED] wrote:
We've grown crystals of the cytochrome bc1 complex in the
presence of glycerol.
I think
I have crystallized a refolded membrane protein in presence of Glycerol. It
did not seem to affect
crystallizability and speed of crystallization.
If you have no luck in presence of glycerol, try to lower the glycerol
concentration without
compromising on the stability of the protein (buffer
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